The invention relates to a device for preventing the introduction of a fuel nozzle for unleaded fuel into the filler neck of a fuel tank of a motor vehicle fitted with a diesel internal combustion engine.
German Published Patent Application Nos. 36 41 274 and 196 39 825 disclose refueling blocks for the filler necks of fuel tanks, which can be used to prevent the introduction of fuel nozzles for leaded fuel or for diesel fuel in motor vehicles which must be refueled exclusively with lead free fuel.
Refueling blocks of this type have been well-established for many years and are still being used to reliably prevent damage to internal combustion engines or catalytic converters of such motor vehicles. However, it should be noted that blocks of this type are relatively simple to construct, since the fuel nozzles for unleaded fuel have a smaller diameter than the fuel nozzles for leaded fuel or for diesel fuel, and therefore introduction of the abovementioned fuel nozzles is in principle already prevented.
It is, however, precisely the other way around in the case of motor vehicles having diesel internal combustion engines, and so unleaded fuel can be supplied without any problem to such vehicles from fuel nozzles having a relatively small diameter. In the case of conventional diesel internal combustion engines which operate in accordance with the precombustion chamber principle this is not a problem which needs to be taken seriously and particularly in winter the addition of up to 30% petrol to the diesel fuel is even recommended so as to prevent the diesel fuel xe2x80x9cbecoming sludgyxe2x80x9d at low temperatures.
However, what is not a problem in the older precombustion chamber diesel internal combustion engines may lead to considerable damage in the case of the common-rail diesel internal combustion engines which are ever more frequently to be found, since the high-pressure pump of such internal combustion engines requires the diesel fuel in order to lubricate it. If a relatively large amount of petrol, in particular unleaded petrol, is then placed in such diesel internal combustion engines, insufficient lubrication may very rapidly occur in the high-pressure pump, with the result that the latter becomes blocked and further operation of the internal combustion engine is not possible. In actual fact, this has already led to broken-down vehicles along with the trouble associated therewith.
Therefore, it is an object of the present invention to provide a device which is used in motor vehicles fitted with a diesel internal combustion engine to prevent fuel nozzles for unleaded fuel from being able to be introduced into the filler neck.
The blocking element according to the present invention is provided to prevent the introduction of a fuel nozzle into the filler neck leading to the fuel tank. Only when the at least one opening element which interacts with the blocking element produces an appropriate signal does the blocking element open and release the access to the filler neck. This result may occur, however, only when a fuel nozzle for diesel fuel is introduced, and the introduction of a fuel nozzle for unleaded fuel, and therefore the refueling of the fuel tank with unleaded fuel, is thereby substantially prevented.
In accordance with the present invention, it is not possible for unleaded fuel to be filled into a motor vehicle having a diesel internal combustion engine, which ensures reliable functioning of diesel internal combustion engines, particularly those operating in accordance with the common-rail principle. One particular advantage of the present invention is that existing fuel nozzles do not have to be retrofitted, as was the case, for example, when unleaded fuel was introduced.
One very functionally reliable configuration of the invention which may be realized with little structural outlay may be produced if there are arranged on the inner circumference of the filler neck at least two opening elements which project into the filler neck and are at such a distance from one another that a fuel nozzle which is introduced into the filler neck and is intended for unleaded fuel does not touch at least one of the opening elements, and in that a fuel nozzle which is introduced into the filler neck and is intended for diesel fuel touches all of the opening elements, in which case, when all of the opening elements are simultaneously touched, the opening elements produce a signal for opening the blocking element.
The at least two opening elements may be configured as contact sensors which produce an electric signal for opening the blocking element. An arrangement of this type which is equally simple and may be converted cost effectively may also be retrofitted in already existing motor vehicles, in which case very reliable functioning would be provided at the same time due the electronically operating contact sensors.
Alternatively, the at least two opening elements may also be configured as projections which protrude into the filler neck and whose distance from one another would be greater than the outer diameter of a fuel nozzle for unleaded fuel, in which case the projections, when touched by a fuel nozzle for diesel fuel, would release the blocking element. This arrangement may also be usable as retrofitted solution and would ensure functioning even independently of a power supply.